Electromechanical jack



E. L. MONNOT ELECTROMECHANICAL JACK.

APPLICATION FILED JAN-15,1920

Patented Dec. 28, 1920.

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UNITED STATES PATENT OFFICE.

EDWARD. Ih MONNOT, OF CANTON, OHIO.

ELECTROMECHANIGAL JACK.

Specification of Letters Patent.

Patented Dec. 28, 1920.

Application filed January 15, 1920. Serial No. 351,708.

of Canton, in the county of Stark and State of Ohio, have inventedcertain new and useful Improvements in Electromechanical Jacks, of whichthe following is a specification.

The improvement relates to lifting jacks for dental, surgical and barberchairs, and

"the object of the improvement is to combine an electric motor directlywith lifting mechanism 1n the base of a chair so that the chair may beraised and lowered by depressing one or the other of two adjacentpedals.

The object of the invention, thus set forth in general terms, isattained by the construction and arrangement illustrated in theaccompanying drawings forming part hereof, in which- Figure 1 is avertical section of the base of a chair showing the motor and the liftinmechanism embodied therein; and

*ig]. 2 an inner end elevation of the motor s owing the case in sectionas on line 2 2, Fig. 1.

Similar numerals refer to similar parts throughout the drawings. 1

Upon the circular base plate 1 of the chair is rotatably mounted thebase standard 2, the intermediate standard 3 and the chair standard 4,which standards telescope and areextensibly guided one within the otherin the usual manner.

A pivot post 5 is centrally mounted on the base plate 1, upon which postis jeurnaled the hub 6 of the cylindric pulley 7 having the flaredfriction flanges 8 annularly arran ed on its periphery.

The lower side of the pulley preferably rides upon ball bearings 9, andthe disk plate 10 may be-secured to the top of the pivot post to stop anupward movement of the pulley thereon.

The upright c lindric screw 11 is mounted on the hub o the pulley andmay be secured thereto by the annular flange 12 and set screw 13; uponthe outer side of which cylindric screw is operatively mounted the nut14 securedzto the lower end of the intermediate standard 3, and insideof the cylindric screw is operatively mounted the screw stem 15 securedto the upper end of the chair standard 4; so that a rotation of thecylindric screw raises and lowers the extensible standards in a wellknown manner.

A motor 16 is mounted on the bottom plate 17 of the V-shaped swingingcarriage havin its side plates 18 and 18 pivoted at 19 an 19* to theupper ends of the stand ards 20 which project upward through slots 21and 21' in the carriage bottom from the supporting plate 22 which plateis extended laterally from one side of the base standard 2.

The upright switch arm 23 is mounted. outside the outer side plate 18upon an extension oijthe pivot 19, and operates between the oppositepairs of jaws 2 1 for closing the electric circuit to operate the motor.The downward extension 25 of the switch arm is pivoted to the stem 27 ofthe inverted T- lever 28, on the arms 29 of which lever are providedpedals as 30 extending laterally through apertures as 31 in the side ofthe motor case 32, which case may be secured to the base standard 2 byscrews 33.

The inverted T-lever is fulcrumed upon the pivot 3projecting from theside plate 18 of the carriage and upon the outer end of this pivot isfixed the head 35 to which is secured the upright spring36. The upperend of this spring operates in the slotted boss 37 on the side of thelever stem 27, to normally hold the same in vertical position; and theadjustable stop screws 38 are provided in the bosses 39, on the outerside plate of the carriage, to limit the movement of the T-lever withreference to the swinging carriage.

The pendent spring 40 is secured at its upper end to the boss 41 on theinner side of the supporting standard 20, and its lower free endoperates in the slotted boss 42 on the carriage bottom to normally holdthe same in central pendent or horizontal position; and the spring 40 isof such greater strength than the spring36, that when one of thepedals'30 is depressed, the swinging platform will remain in normalposition while the stem of the T-lever is deflecting the weaker spring36 until the opposite arm 29 impinges the corresponding stop screw 38;whereupon a further depression of the same pedal swings the motorcarriage upon its pivotal supports 19.

In the normal position of the arts, the conical friction pinion 43 onthe inner end of the motor shaft is positioned freely midway between theflared friction flanges 8 on the cylindric pulley 7 as shown in Fig. 1;and it is evident that a swinging or tilting of the motor carriage willbrmg the pinion into frictional engagement with one or the other of theflared flanges for operating the lifting mechanism in one direction orthe other.

For operating the motor to raise the chair standards, one of the pedalsis depressed by the foot and the T-lever is turned in one directionagainst the resistance of the relatively weak spring 36 until the switcharm enters between one of the pairs of jaws 24 thus closing the circuitand starting the motor; whereupon the opposite arm 29 of the T- leverimpinges the corresponding stop screw 38 and a further depression of thesame pedal swings the motor carriage until the pinion i3 impinges thecorresponding friction flange for operating the lifting mechanism toraise the chair; and it is obvious that a depression of the other pedalin like manner will first start the motor and then reversely operate thelifting mechanism to lower the chair.

Means are provided for stopping the operation of the lifting mechanismas the'chair standards approach the limit of their proper movement; andsuch means ma comprise the hell crank it mounted in the ease standaid 2having one arm protruding into the vertical slot 46 in the intermediatestandard, and the other arm 4-7 depending to a pivotal connection withthe rod t8 which slidably extends through the guide eye d9 on the upperend of the carriage side plate 18.

Stop nuts 50 are adjustahly spaced and locked on the rod e8 on each sideof the guide eye, so that when the ends of the slot i6 impinge the armof the hell crank ed, the rod 48 will be moved endwise and thecorresponding stop nut thereon will operate against the -g 2;uide eye e9to swing the motor carriage into normal position, which frees thefriction pinion from contact with the pulley flange and stops theoperation of the lifting mechanism. I

The automatic and positive action of ping means, raises the pedal whichhas n depressed and thus informs the opera that limit of the movement ofthe chair tandards has been reached, so t e foot he removed from thepedal, whereupon eit the action of the spring 36 returns the switch armto normal position which opens the circuit and stops the motor.

I claim:

1. Lifting mechanism including an operating pulley having two peripheralfriction flanges thereon, a swinging carriage with an electric motorthereon having a friction inion normally located freely between thefriction flanges, two pairs of switch jaws in the motor circuit on thecarriage and a switch arm normally located freely between the jaws, andmeans for initially swinging the switch arm into either pair of aws forstarting the motor, and subsequently swinging the motor carriage tocontact the friction pinion with one of the friction flanges foroperating the lifting mechanism one way or the other.

2. Lifting mechanism including an operating pulley having two peripheralfriction flanges thereon, a spring controlled swinging carriage with anelectric motor thereon having a friction pinion normally located freelybetween the friction flanges, two pairs of switch jaws in the motorcircuit 'on the carriage and a switch arm normally located tion flanges,two pairs of switch jaws in the motor circuit on the carriage and aswitch normally located freely between the jaws, means for initiallyswinging switch arm into either pair of jaws for starting the motor, andsubsequently swin ing the motor carriage to contact the fricf thefriction flanges 11 h mechanism one way means actuated by the lift mstopping the same as it is limit of its movement in n Monitor.

